Source: https://guthlabs.ai/docs/instruments/diffraction-limit-optimal-aperture-calculator/mechanism/

instrument mechanism / verified-clean

# Diffraction Limit / Optimal Aperture Calculator mechanism

The inspectable method record for Diffraction Limit / Optimal Aperture Calculator, kept separate from implementation and qualification.

Status: **VERIFIED_CLEAN**Lifecycle: **verified-clean**

## Model scope

The honest-label warning about physical-optics approximation and lens quality is appropriate but incomplete. The product must disclose the explicit diffraction criterion and resolve the contradiction between N=pixelPitch/(1.22λ) and Airy diameter=2.44λN before claiming a standard diffraction-limit calculation.

- The stated formula N≈pixelPitch/(1.22*λ) is not consistent with the stated Airy-disk diameter formula when the criterion is that the Airy disk diameter equals one pixel. Substitution gives Airy diameter=2.44*λ*(pixelPitch/(1.22*λ))=2*pixelPitch. Under the one-pixel Airy-diameter criterion, the corresponding formula is N≈pixelPitch/(2.44*λ).

- The phrase "begins to visibly limit resolution" does not define a unique optical criterion. Depending on the chosen criterion, the relevant comparison may involve Airy-disk diameter, Airy radius, pixel pitch, or sensor Nyquist frequency; the criterion must be stated explicitly.

- The sensor megapixels-and-size input path does not specify whether size means active width and height, diagonal, or nominal format size, nor does it specify the aspect ratio and active-area assumptions needed to derive pixel pitch.

## Units and conventions

- Pixel pitch and wavelength must use the same length unit; with λ=0.00055 mm, pixel pitch must be supplied in millimetres or converted to millimetres.

- The default λ≈0.00055 mm means 550 nm monochromatic green light; real scenes and sensors respond over a wavelength band.

- For megapixel-plus-size calculations, the sensor dimensions are assumed to be active imaging width and height in millimetres, pixels are square, and the stated megapixel count is the active pixel count.

## Inspectable vector

One of 4 source-bound review vectors:

````
{
  "inputs": {
    "manual_pixel_pitch_mm": 0.004,
    "wavelength_mm": 0.00055
  },
  "expected_outputs": {
    "diffraction_limited_f_number": 5.961252,
    "airy_disk_diameter_mm": 0.008
  },
  "working": "1.22*λ = 1.22*0.00055 = 0.000671 mm. N = 0.004/0.000671 = 5.961252. Airy diameter = 2.44*0.00055*5.961252 = 0.008000 mm, equivalently 2*0.004 = 0.008000 mm."
}
````

## Failure boundary

**BREAK_CLAIMED** · SELF_FLAGGED

The specification does not state validation behavior for zero megapixels, zero or negative pixel pitch, or other nonphysical inputs. Zero megapixels creates a division-by-zero during derived pixel-pitch calculation, while negative pixel pitch produces sign-dependent and physically invalid outputs unless explicitly rejected or converted to an absolute magnitude.

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/diffraction-limit-optimal-aperture-calculator/>)[03**Implementation**](<https://guthlabs.ai/docs/instruments/diffraction-limit-optimal-aperture-calculator/implementation/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/diffraction-limit-optimal-aperture-calculator/qualification/>)

## Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

- `VERIFIED_LEDGER.json`

- `evidence-tranche5/tranche5-results.json`

- `BOUNDARY_HAZARD_CATALOG.json`